Introduction of a digital near-vision reading test for normal and low vision adults: development and validation

BACKGROUND: MNREAD is an advanced near-vision acuity chart that has already been translated and validated in Greek language. Considering that no validated Greek digital near-vision test exists, our primary objective was to develop and validate a digital near-vision reading test based on the fundamental properties of the Greek printed MNREAD (MNREAD-GR). METHODS: This is a prospective, comparative study. A digital near-vision chart was developed (Democritus Digital Acuity Reading Test – DDART) with text size calibration, audio recording for automatic reading timing, as well as automatic calculation of reading acuity (RA), maximum reading speed (MRS), critical print size (CPS) and reading accessibility index (ACC). Normal and low vision subjects participated in the validation process, responding to MNREAD-GR and DDART at the same day, at a 40 cm viewing distance. Differences in all parameters between the charts were compared with t-test and intraclass correlation coefficients (ICCs). Within 15 days, all participants responded again to DDART in a different set of sentences to assess its test-retest reliability. RESULTS: One hundred patients (normal vision group - NVG: 70 patients; low vision group - LVG: 30 patients) responded to both reading tests. Non-significant differences were detected for all parameters between DDART and MNREAD-GR except for MRS and ACC that were significantly higher in MNREAD-GR in NVG (p < 0.01). NVG participants demonstrated sufficient ICCs that ranged from 0.854 to 0.963, while LVG demonstrated ICCs for RA, ACC, MRS and CPS equal to 0.986, 0.894, 0.794 and 0.723, respectively. All parameters calculated with DDART demonstrated excellent test-retest reliability (ICCs: 0.903 – 0.956). CONCLUSIONS: The proposed reading test presented comparable validity and repeatability to MNREAD-GR suggesting that it can be used both in normal and low vision Greek patients. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04242836. Registered 24 January 2020 – Retrospectively registered.